1. The Field of the Invention
This invention relates to the field of optical systems, and more particularly to methods and apparatus for monitoring the power of a multiple optical signals.
2. The Relevant Technology
Various forms of optoelectronic devices have been developed and have found widespread use including, for example, semiconductor lasers, semiconductor photodiodes, semiconductor photo detectors, etc. For some applications, an optoelectronic emitter such as a semiconductor laser is coupled to an optoelectronic detector (e.g., photodiode or Resonant Cavity Photo Detector) through a fiber optic link, free space, etc. These configurations provide a high-speed communication path, which, for many applications, can be extremely beneficial. Optoelectronic emitters and detectors may also be used in a wide variety of other applications including, for example, writing/reading data in recorded media applications, performing assay analysis on chemical and biological materials, and many others. It is known that the power of many optoelectronic emitter(s) tend to vary over time. A variety of reasons contribute to this including, for example, changing operating conditions such as operating voltage, operating temperature, as well as device degradation or failure, etc.
For many applications, it is desirable to maintain a specific, constant or at least known optical output power, as this can significantly increase the reliability and/or accuracy of the system. For example, in optical communications applications, if the power of one or more of the data channels falls outside of a desired range, the reliability of the communications link can significantly degrade. In some systems, it is possible to provide a separate detector to monitor the optical output power of each optoelectronic emitter. However, this is not always possible, and in many cases, can add significant cost to the system. For example, providing a separate photodiode for each optoelectronic emitter in an optoelectronic emitter array can significantly increase the pitch of the array because of increased active area and increased wiring congestion.